Throat microphone



y 1939- s. BALLANTINE 2,165,124

THROAT MICROPHONE Original Filed Feb. 12, 1935 Patented July 4, 1939 UNITED STATES PATENT OFFICE Original application February 12, 1935, Serial No. 6,246. Divided and this application September 30, 1937, Serial No. 166,667

Claims.

This invention relates to throat microphones and particularly to those features of a throat microphone assembly that prevent inadvertent. actuation of the microphone by wind and aerial 5 sound waves.

This application is a division of my copending application Serial No. 6,246, filed February 12, 1935, now Patent No. 2,121,779. Throat microphones and methods of operating the same are described in the prior application and reference is made to the same for the detailed description of one type of contact microphone with which th present invention is useful.

An object of the present invention is to provide 16 a throat microphone which precludes inadvertent operation of the transducer element or elements by wind or aerial sound waves. An object is to provide throat microphones including pads or guard members that contact the neck of the 20 operator to exclude wind and air currents from the point at which the vibration-transmitting member of the transducer unit contacts the operators neck. A further object is to provide a throat microphone including one or a pair of transducer units, a flexible casing for housing the unit or units and supporting the same on the operators neck, and wind guard members atthe periphery of the flexible casing to prevent wind and air currents from the region between the operators neck and the casing.

These and other objects and advantages of the invention will be apparent from thev following specification when taken with the accompanying drawing in which:

Fig. 1 is a front elevation of an embodiment of the invention in place on the operator's neck;

Fig. 2 is a perspective view of thedouble unit microphone and supporting band;

4 Fig. 3 is a transverse section through a micro- 40 phone, in place upon the larynx, and illustrating a satisfactory construction of the microphone covering; and

Fig. 4 is a similar section showing an alternative construction.

The new microphone is adapted to be worn around the neck like a collar, as shown in Fig. 1, but other methods of support may be employed. In the particular embodiment of the invention which I have selected for purposes of illustration, the microphone M has the general form of a narrow band in which two mechano-electrical transducers are symmetrically arranged, and an adjustable elastic band B is sewed to the microphone to form a collar that may be placed around the neck in such a way that the microphone units trade-mark Bakelite. I

Besides protecting and holding the units in place, this covering also reduces noise due to aerial sound waves and the impact of wind 10 against the microphone;' as a result and also because of the fact that the microphone is designed to be actuated by mechanical vibrations rather than aerial sound waves. the microphone is very insensitive to extraneous noise. This is 15 an important advantage when used in noisy locations, such as open cockpit airplanes, where the noise picked up by microphones of conventional types has been a serious problem. With my microphone, used in an airplane, the motor and 20 propeller noises are almost inaudible, the only extraneous noise heard is a low intensity sound due to the impact of wind against the microphone, not loud enough to be troublesome. I have found that a large part of the wind noise is due to 25 wind getting in the space between the transducers and the neck. The constructions herein described are intended to prevent the entrance of wind into this space. By these means the Wind noise is almost entirely eliminated. 30

The two transducer units of the microphone are of identical construction and, as shown in end elevation in Figs. 3 and 4, take the form of small metal cases I having grooved back walls 2 in which is located the cable 3 that connects the 35 microphone to an amplifier, not shown. Vibration-transmitting buttons 4 project from the transducer elements to the exterior of the cases I at the inner side of the microphone.

The cases I are loosely supported within the flexible casing formed by sewing an outer strip 5 and inner strip 6 of soft material, such as glove leather, together along their edges. The inner strip 6 has openings 8 through which the buttons 4 extend, and a thin membrane 1 extends 5 over the buttons and is sewed or cemented to the inner flexible wall 6. One end of the casing is sewed to an end of the band B and the parts of a snap fastener 9 are secured to the other ends of the casing and band B, respectively.

Noise due to the entrance of air into the space between the neck and the microphone is reduced or eliminated by shaping the edges of the flexible casing to obtain a good contactwith the neck. As shown in Fig. 3, a roll is formed at the edge of the casing by first sewing a roll strip ill to the edge of the inner strip 6 by stitching H, placing the strips 5, 6 and 1 upon each other and rolling the strip Ill back upon itself to enclose the meeting? eS/aird then completing the assembly by stitchmg' I2 which passes through the rear edge of strip l and the strips 5, 6 and lof the casing. The rolled strips 10 rest against the neck, indicated at I3, and form a seal against the wind.

A suitable seal may also be formed by surrounding the central contacting, or vibration transmitting, member by a resilient pad I4 as shown in Fig. 4. Sponge rubber or a soft felt, such as corn felt, are suitable materials for the pad. The wind-screening pad may be cemented or otherwise fastened to the assembly, as shown in Fig. 4, or may be made part of the housing of the microphone. The essential requirement is that when the central vibration transmitting member is in firm contact with the throat the encircling pad is also in firm contact with the skin to prevent the ingress of wind.

It is also helpful to fill the space between the microphone case I and the flexible casing wall 5 with sound insulating material 15 to reduce noise due to the impact of wind directly upon .the microphone. -This material may take the form of sponge rubber or felt and may be secured to and form a part of the casing.

While I have described a preferred embodiment of the invention, it will be apparent that there is considerable latitude in the design and construction of the device and that variations, additional to those herein specifically mentioned, may be made Without departure from the spirit of my invention as set forth in the following claims.

I claim:

1. In a throat microphone, a mechano-electrical transducer including vibrating means adapted to be actuated by mechanical vibrations of the throat'due to the voice-means for supporting said vibrating means in contact with the throat, and means preventing wind and aerial sound waves from entering the space between the said transducer and the neck, said means comprising a pro-- tuberance encircling said vibrating means at its point of contact with the throat and projecting from the transducer into sealing engagement with the neck when the microphone is in an operating position.

2. In a throat microphone, a mechano-electrical transducer including vibrating means adapted to be actuated by mechanical vibrations of the throat due to the voice, means for supporting said vibrating means in contact with the throat, and means preventing wind and aerial sound waves from entering the space between the said transducer and the neck, said means comprising a resilient cushion encircling the said vibrating means at its point of contact with the throat and projecting from the transducer into sealing engagement with the neck when the microphone is in an operating position.

3. The invention as claimed in claim 1, wherein the last means comprises sponge rubber projecting from the transducer into sealing engagement with the neck when the microphone is in an operating position.

4. In a throat microphone, a mechano-electrical transducer comprising vibrating means adapted to be actuated by the mechanical vibrations of the throat due to the voice, a protective casing forvsaid transducer, means for supporting the casing on the neck with said vibrating means in contact with the throat, and means preventing wind and aerial sound waves from entering the space between the protective casing and the neck, said last means comprising sponge rubber attached to said casing and projecting therefrom into sealing engagement with the neck of the operator when the microphone is in operating position.

5. In a throat microphone, a mechano-electrical transducer comprising vibrating means adapted to be actuated by the mechanical vibrations of the throat due to the voice and an inertial sup port for said vibrating means, a protective covering of flexible leather for said transducer adapted to be worn around the neck, and means comprising a. rolled edge strip on said fiexible leather covering for preventing wind and aerial sound waves from entering the space between the protective covering and the neck.

STUART BALLANTINE. 

